ABSTRACT
Membrane proteins are amphiphilic macromolecules incorporated vectorially in the lipid membrane in a quasi-solid state. Solubilized membrane proteins form so-called mixed micelles with the detergent. Complete solubilization of a membrane protein is achieved when the protein is not further complexed by the detergent, i.e., when there is not more than one protein in a mixed micelle. Crystals of membrane proteins contain, as a constituent part, the detergents bound to the protein and necessary for the solubilization; when one tries to dialyze the detergent out of the crystals, they dissolve or collapse. At low concentrations, detergents in water form small colloidal aggregates called micelles. The effects which drive detergents into micellization are related to the structure of water, and thus micelle formation is a manifestation of the hydrophobic effect. Depending on concentration and temperature, detergents may not only form micelles in water, but also aggregates of extended, spatially ordered structure termed mesophases.
